ATLANTIC CITY — In a normal month, casinos rake in about 10 percent to 15 percent of the chips players buy at a blackjack table, experts say.

But last month, the take at two Atlantic City casinos flew in the face of conventional wisdom that "the house always wins."

The Tropicana lost more than $1.86 million at its blackjack tables, while the Borgata narrowly avoided a loss, collecting less than $1 million on nearly $75 million in chips purchased, just over a 1 percent take. Most of the other casinos in Atlantic City did much better at the blackjack tables in April, led by Caesars, which made $7.6 million.

Daniel Heneghan, a spokesman for the state Casino Control Commission, said the proportion of the Tropicana’s loss was unprecedented in the state since the inception of casino gambling in 1978.

"It’s extraordinarily unusual for a casino to lose money at the game of blackjack in a particular month," said Heneghan, who has worked for the commission for 15 years.

Outgoing Tropicana CEO Mark Giannantonio told the Press of Atlantic City his casino lost almost $6 million to one man, whom he would not identify. Representatives from the two casinos did not respond to calls from The Star-Ledger.

"A casino can have a losing day, but it’s maybe once or twice a year. Anything that is longstanding where the (winning) percentage goes down for a month, or two months straight, and I’m looking at other things," said Jim Wortman, director of gaming education and research at the Conrad N. Hilton College of Hotel and Restaurant Management at the University of Houston.

Wortman, who worked for more than a decade at Atlantic City casinos and once trained dealers at the Tropicana, said the numbers should make casino managers suspicious.

"I just want to make sure the guy who made $6 million is that good, and not that he’s cheating or our dealers are that bad," Wortman said. "Generally, I would have more eyes on this guy than if he’s sitting there naked."

But William Eadington, a professor at the University of Nevada, Reno, said the threat of surveillance would stop most cheaters in their tracks.

"I’d be very surprised if this were a cheat of one kind or another because it’s too high visibility," Eadington said.

He also said the blackjack results at the two casinos could be related.

"The fact (Borgata) only won $1 million makes you think they had one or more players like the guy at the Tropicana," Eadington said. "The one thing that is not likely is that other blackjack players played better. What is likely is that one or a very small number of players came in with large wagers and played lucky."

Other experts said that since casinos aim to bring in high rollers, the occasional loss is to be expected.

"When you attempt to target the high end player market, volatility will be part of it," said Michael Pollock, publisher of the Gaming Industry Observer. "It’s not unprecedented that one player could have such an impact."

Winning blackjack players have caught the public attention before; a team of students from the Massachusetts Institute of Technology who studied the game and systematically beat casinos was profiled in the book "Bringing Down the House" and the movie "21," starring Kevin Spacey.

"It’s one of the games you can defeat by strategy," Wortman said. "The strategy there is not anything new. It’s called card counting."

In card counting, a player tracks which cards have been played and bets when favorable cards are due. Sometimes, a player is assisted by several "spotters" nearby who look on and signal them.

Eadington said he doubts that type of card counting was the case at the two casinos last month.

"The classic "Bringing Down the House" kind of scenario is a bit farfetched," he said. "That said, to get that kind of performance you’d have to have very confident players."

Instead, Eadington said, the player who won $6 million likely was approved for a very high betting limit — a calculated gamble on the casino’s part.

"This is always an interesting risk management decision for casinos: do you accept big wagers. If you accept big wagers, you have short-term volatility," he said. "That’s sort of the philosophy here. Does the casino have the cojones to ride out the short-term volatility? They’re offering a game where they will win in the long run if they can get there."